Adjustable mast for drilling on hoisting with rigid stay

ABSTRACT

A base has rails extending longitudinally in one direction and a drilling machine assembly is supported on the rails for movement in this direction between a forward drilling position and a retracted hoisting position, the drilling machine assembly including a drilling head to grip and rotate an upright drill rod when in the drilling position. Power means are provided to move the drilling machine between its two positions. An upright mast has its lower end pivotally connected to the drilling machine assembly by a first pivot connection to move back and forth with the assembly, and a rigid stay is pivotally connected at its upper end, by a second pivot connection, to an upper part of the mast and is pivotally connected, at its lower end, by a third pivot connection to an anchorage fixed relative to the base, so that the mast is rotated about the second pivot axis upon movement of the drilling machine assembly between the drilling and hoisting positions. A hoist sheave support is suspended from the mast for swinging about the second pivot connection, and hoist sheaves are mounted on the sheave support. When the drilling machine assembly is in the drilling position, the first pivot connection is spaced forwardly through a preselected distance from a vertical plane through the second pivot connection and, when the drilling machine assembly is in the hoisting position, the first pivot connection is spaced an equal distance rearwardly from this vertical plane, which assures that the second pivot connection and the sheaves remain in the same location for both the drilling and hoisting positions of the drilling machine assembly.

United States Patent 1 Rice [ Sept. 11, 1973 ADJUSTABLE MAST FORDRILLING ON I-IOISTING WITH RIGID STAY Primary Examiner-Ernest R. PurserAtt0rney-John J. McGlew et al.

[57] ABSTRACT A base has rails extending longitudinally in one directionand a drilling machine assembly is supported on the rails for movementin this direction between a forward drilling position and a retractedhoisting position, the drilling machine assembly including a drillinghead to grip and rotate an upright drill rod when in the drillingposition. Power means are provided to move the drilling machine betweenits two positions. An upright mast has its lower end pivotally connectedto the drilling machine assembly by a first pivot connection to moveback and forth with the assembly, and a rigid stay is pivotallyconnected at its upper end, by a second pivot connection, to an upperpart of the mast and is pivotally connected, at its lower end, by athird pivot connection to an anchorage fixed relative to the base, sothat the mast is rotated about the second pivot axis upon movement ofthe drilling machine assembly between the drilling and hoistingpositions. A hoist sheave support is suspended from the mast forswinging about the second pivot connection, and hoist sheaves aremounted on the sheave support. When the drilling machine assembly is inthe drilling position, the first pivot connection is spaced forwardlythrough a preselected distance from a vertical plane through the secondpivot connection and, when the drilling machine assembly is in thehoisting position, the first pivot connection is spaced an equaldistance rearwardly from this vertical plane, which assures that thesecond pivot connection and the sheaves remain in the same location forboth the drilling and hoisting positions of the drilling machineassembly.

5 Claims, 5 Drawing Figures PATENTEDSE" 3.757. 873

SHEET 2 UF 3 ADJUSTABLE MAST FOR DRILLING ON HOISTING WITH RIGID STAYBACKGROUND OF THE INVENTION 1. Field of the Invention This inventionrelates to drilling apparatus and particularly to core drillingapparatus used in exploratory drilling.

2. Description of Prior Art The invention has particular but notexclusive application to small drilling rigs and is concerned with rigsof the type incorporating a drilling machine which can be mobed back andforth between a forward drilling position and a rearward hoistingposition. In apparatus of this type the drilling machine assemblyusually comprises a drive motor which drives a hoist drum at the rear ofthe assembly and a drilling head at the front of the assembly. Duringdrilling the machine assembly is located in its forward position and thedrilling head is then located directly over the hole being drilled. Thedrilling head grips and rotates the drill string which extendsdownwardly through it and the drill rod is supported by a hoisting ropepassed over one or more sheaves at the top of a mast andthen down to thehoist drum. When the drill string is to be retrieved from the hole, thewhole drilling machine assembly is drawn or racked back to its rearwardposition and the drill string is hoisted directly by the hoist rope pastthe retracted drilling head. During both drilling and hoistingoperations the hoist rope connected to the drill string must beaccurately aligned with it so that the head sheave wheel from which itextends must be very accurately positioned with respect to the hole.Furthermore this head sheave wheel must be in precisely the sameposition during both drilling and hoisting operations. Hence at leastthe top part of the mast must be accurately located in the same positionfor both operations. In order to achieve this it is usual to provide alarge and robust support frame firmly set on the ground.

SUMMARY OF THE INVENTION The present invention provides an arrangementwhereby the respective head sheave wheel is accurately positionedwithout the need for a complicated supporting frame. The arrangementaccording to the present invention can also be such as to avoid foulingof the mast by the top drill rod when the. drilling machine assembly isdrawn backto its hoisting position.

According to the invention there is' provided drilling apparatuscomprising a base, a drilling machine assembly mounted on the base andincluding a drilling head, an upright mast pivotally connected at itslower end to the machine assembly by a first pivot connection, an armpivotally connected at one end by a second pivot connection to an upperpart of the mast and pivotally connected at its other end by a thirdpivot connection to a fixed anchorage, and hoist sheave means supportedfrom said part of the mast, and wherein the drilling machine assembly ismovable transversely of the mast from a drilling position in which thefirst pivot connection is in a first position and the second pivotconnection is in a second position to a hoisting position in which thefirst pivot connection is in a third position spaced from the firstposition and spaced from the second position by a distance equal to thedistance between the first and second positions so that the secondpivotconnection is disposed in said second position. whereby the sheavemeans is in the same position for the drilling and hoisting positions ofthe drilling machine assembly. Preferably, said first and thirdpositions are spaced one to either side of, and equally from,

a vertical plane through the second position.

In order that the invention may be more fully explained, one particularembodiment will now be described in some detail with reference to theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, FIG. 1 is a sideelevation of a drilling apparatus shown in condition for drillingoperations;

DESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated apparatuscomprises a drilling machine assembly denoted generally as ll andmounted on a fixed base 12 in a manner to be described below. Themachine assembly 11 is of conventional construction comprising a drivemotor 13 which drives a hoist 14 and a drilling head 16. An upright mast17 is pivotally connected at its lower end to the machine assembly 1 1by a pivot connection 18. For the most part mast 17 is of light-weightbox girder construction comprising longitudinal stringers 19 and latticebracing members 21, but its lower end is formed by a bracket 22connected to the machine assembly 11 by a pivot pin forming the pivotconnection 18 about an axis 24.

The upper part of mast 17 is pivotally connected at 26 to the upper endof a stay arm 27 which is inclined at an acute angle to the mast and ispivotally connected at its bottom end to an anchor 29 by a pivotconnection 28. Anchor 29 is carried byamount 31 which is fixed relativeto the machine base 12 either by being connected directly to it or bybeing set firmly in the ground. Arm 27 comprises a central girdersection 32, a bottom adjustment portion 33.and an upper portion 34. Thelower adjustment portion 33 comprises a screw threaded stem 36 clampedto the bottom of the arm portion 32 by lock nuts 37 and screw-fittedinto an internal thread socket member 38 which is connected to theanchor 29 by a ball joint forming the pivot connection 28.

The upper part 34 of arm 27 is bifurcated so as to have two end portions41 extending one to either side of the upper part of the mast andpivotally connected at their upper ends to the mast by a composite pivotpin 42. The composite pivot pin comprises a central tube 43 to which theupper ends of the arm parts 41 are clamped by studs 44. 'Pivot tube 43extends through a bearing tube 46 which is fixed between side plates 47on the upper part of the mast. Thus the mast l7 and stay arm 27 canpivot relative to one another about the axis 48 of the pivot and bearingtubes 43,46.

A cradle 49 carrying a pair of head sheaves 50, 51 hangs from the pivotbearing tube 46 at the upper end of the mast. The cradle 49 comprises aframe 52 in which the sheaves 50, 51 are journalled and a pair of yokemembers 53. The yoke members are of generally inverted U-shape andextend over the pivot bearing tube 46 so that the whole cradle 49 hangsfreely from the pivot bearing tube and is free to swing under gravityabout the axis 48 of the tube. A cable 55 extends from the hoist 14 tothe sheave 50. It passes around sheaves S and 51 and then downwardly toa connection to the top drill rod whence it supports the drill string.

FIG. 1 shows the apparatus in a condition ready for drilling. In thiscondition the main part of the mast is vertical and the sheave 51 ispositioned directly above the hole being drilled so that the drillstring is supported by cable 55 in accurate alignment with the hole.

For hoisiting operations the whole of the machine assembly 11 is drawnback along base 12 and away from the hole to the position shown in FIG.2. The drilling head 16 is thus drawn back from its position over thehole and the drill rods can be hoisted directly past it. However thesheave 51 should be accurately positioned directly over the hole notonly during drilling operations but also during hoisting. It istherefore most desirable that the position of the sheave 51 be inprecisely the same position when the drilling machine is drawn back forhoisting operations as when it is in its forward position for drilling.The geometry of the illustrated arrangement is carefully arranged toproduce this result.

It will be seen from FIG. 1 that when the apparatus is in condition fordrilling with the machine assembly 11 in its forward position, the pivotaxis 24 at the lower end of the mast is not vertically below the pivotaxis 48 at the top of the mast but is positioned forwardly from such aposition through a distance X. Thus although the main part of the mastis vertical the mast effectively serves as a link which is downwardlyand forwardly inclined through a small angle. When the drilling machineassembly 11 is pulled back the pivot connection 18 is moved to aposition 57 which is spaced horizontally from the forward position ofthat pivot point through a distance of 2X. The forward and rearpositions of the pivot connection 18 are thus spaced one to either sideof, and equally from, a vertical plane through the second position.

It will be appreciated that the forward and rear positions of the pivotconnection 18 both lie on the same circular arc centered on the positionof axis 48. In other words, even after pivot connection 18 has movedfrom its forward position to its rear position, it is spaced by the samedistance from the original position of axis 48. Therefore the effect ofthe linking of the mast to stay arm 27 is that the pivot connection 26at the top of the mast will he in precisely the same place for the twopo sitions of the drilling machine assembly although it may in fact movewhile the machine assembly is being moved between these forward and backpositions. The drilling machine assembly could be drawn back away fromthe hole in a straight horizontal path. In this case the pivot position26 would in fact move upwardly through the first half of the movement ofthe assembly and would then return back to its original position.Because the position of the pivot bearing tube 16 is precisely the samefor the forward and back positions of the drilling machine the sheavecarriage 49 also hangs in precisely the same position although the masthas moved relative to it.

The drilling machine assembly 11 is in fact not drawn back in a straighthorizontal path. As can be seen in FIGS. 4 and 5 the assembly 11 ismounted on the base 12 via front support collars 61 and rear supportcollars 62 which slide on front tubular rails 63 and rear tubular rails64 fitted to the base. The rear rails 64 are inclined upwardly andrearwardly so that the whole of the drilling machine assembly 11 iscanted when it is drawn back to its rear position. The arrangement issuch that the pivot connection 18 adopts position 57 when the assembly11 is drawn back to its fullest extent, i.e., the same position which itwould adopt if the assembly were drawn back in a straight line. It willbe appreciated that in order to maintain a straight line motion of thepivot joint 18 the machine assembly 11 would have to be mounted on acurvilinear track support. By the provision of the straight supportrollers the pivot connection 18 will go through transient posilions awayfrom a straight line path but when the assembly has been drawn to itsrear-most position the pivot connection 18 is in the position 57 so thatthe pivot sheave 51 is correctly aligned above the hole.

The canting of the assembly 11 is provided in order to avoid the top ofthe drill string from fouling the mast during racking back. It is usualto leave the top drill rod engaged with the drilling head during rackingback to avoid the necessity to break the water supply and controlconnections made to it. The top drill rod 60 is unscrewed from theremainder of the drill string and is then drawn back with the drillinghead and out of the way before the remainder of the drill string 65 ishoisted as shown in FIG. 2. Ifthe drilling machine assembly 11 weredrawn back in a straight path the top of its top rod would foul the topof the mast. However, in the illustrated arrangement the tilting of thedrilling machine assembly 11, and therefore the drilling head 16, issufficient to cant the top drill rod so that it clears the mast.

As will be seen by comparing FIGS. 1 and 2, the drilling head tiltsthrough a rather smaller angle than does the mast as the drillingmachine assembly is racked back. When the assembly 11 is in the drillingposition the top drill rod 60 is generally parallel with the front faceof the mast but when assembly 1 1 has been racked back it is inclined tothe front face of the mast. This is necessary to allow the remainder ofthe drill string 65 to be hoisted without fouling the top of drill rod60. The tilting movement of the drilling head 16 in fact corresponds toswinging movement about a pivot located about twice as far away as thetop of the mast.

Because of the tilting movement of the machine assembly 11, it ispossible to employ a simple box section mast which can be a light-weightconstruction. If the machine assembly 11 were not canted during rackingback it would be necessary to form the mast with a recessed constructionto receive the top of the drill rod and this would necessitate a mast ofmuch more complicated and heavier construction.

The machine assembly 11 is driven backwardly and forwardly along therails 63,64 by operation of a double acting hydraulic ram 66 pivotallyconnected between the assembly and the base 12. It will be seen thatsupport collars 61, 62 are not cylindrical but their internal surfacesare conically tapered at their ends 61A, 61B, 62A, 62B and that therails are mounted between members which define similarly tapered plugs68A, 68B, 69A, 69B. When the machine assembly 11 is driven forwardly thetapered ends 61A, 62A engage the tapered plugs 68A, 69A whereby themachine assembly is positively located and firmly locked in positionmerely by maintaining hydraulic pressure of the ram 66. Similarly, theassembly is positively located and firmly locked in its rearwardposition by the engagement of the tapered surfaces 61B, 623 with theplugs 68B, 693. There is therefore no need to fasten and unfastenclamping means before and after each racking operation as inconventional apparatus.

1 claim:

1. Drilling apparatus comprising in combination, a base; rail meansmounted on said base to extend longitudinally in one general direction;a drilling machine assembly supported on said rail means for movementback and forth in said general direction; stop means limiting movementof said drilling machine assembly along said rail means between aforward drilling position and a retracted hoisting position; saiddrilling machine assembly including a drilling head to grip and rotatean upright drill rod when in thedrilling position; power means operaableto move said drilling machine assembly between its drilling and hoistingpositions; an upright mast having its lower end pivotally connected tosaid drilling machine assembly at a first pivot connection, to move backand forth with said drilling machine assembly; a rigid stay having oneend pivotally connected, by a second pivot connection, to an upper partof said mast, and having its other end pivotally connected, by a thirdpivot connection, to an anchorage fixed relative to said base, wherebysaid mast is rotated about said second pivot connection responsive tomovement of said drilling machine assembly between its drilling andhoisting positions; a hoist sheave support suspended from the upper partof said mast to be swingable about said second pivot connection;-andhoist sheave means mounted on said sheave support; said rail means andsaid stop means defining the drilling and hoisting positions of saiddrilling machine assembly in a manner such that, when said drillingmachine assem-,

bly is in its drilling position, said first pivot connection is in afirst position and said second pivot connection is in a second positionand, when said drilling machine assembly is in its hoisting positio,said first pivot connection is in a third position spaced from saidsecond position by a distance equal to the spacing between said firstand second positions, whereby said mast and said stay serve as a linkageassuring said second pivot connection remaining in said second positionso that the location of said sheave means is identical in both the backand forth in said general direction; stop means limiting movement ofsaid drilling machine assembly along said rail means between a forwarddrilling position and a retracted hoisting position; said drillingmachine assembly including a drilling head to grip and rotate an uprightdrill rod when in the drilling position; power means operable to movesaid drilling machine assembly between its drilling and hoistingpositions; an upright mast having its lower end pivotally connected tosaid drilling machine assembly at a first pivot connection, to move backand forth with said drilling machine assembly; a rigid stay having oneend pivotally connected, by a second pivot-connection, to an upper partof said mast, and having its other end pivotally connected, by a thirdpivot connection, to an anchorage fixed relative to said base, wherebysaid mast is rotated about said second pivot connection responsive tomovement of said drilling machine assembly between its drilling andhoisting positions; a hoist sheave support suspended from the upper partof said mast to be swingable about said second pivot connection; andhoist sheave means mounted on said sheave support; said rail means andsaid stop means defining the drilling and hoisting positions of saiddrilling machine assembly in a manner such that when said drillingmachine assembly is in its drilling position, said first pivotconnection is spaced forwardly a predetermined distance from a verticalplane through said second pivot connection and transverse to saidpredetermined distance and, when said drilling machine is in itshoisting position, said first pivot connection is spaced through adistance equal to said predetermined distance rearwardly from saidvertical plane, said mast and said stay serving as a linka'age to assuresaid second pivot connection, and consequently said sheave means,remaining in the same location in both the drilling and hoistingpositions of said drilling machine assembly.

'3. Drilling apparatus, as claimed in claim 2, in which said drillingmachine assembly includes a winch drum and said sheave means comprises apair of sheave wheels mounted for rotation on said sheave support; oneof said sheave wheels being located directly above said winch drum whensaid drilling machine assembly is in its hoisting position; the other ofsaid sheave wheels being located directly above the drill hole duringboth the drilling and hoisting operations.

4. Drilling apparatus, as claimed in claim 2, in which said drillingmachine assembly in moving from the drilling position to the hoistingposition rotates about a horizontal transverse axis to tilt saiddrilling head in the same direction as the direction of tilt of saidmast away from its original upright position resulting from saidmovement of said drilling machine assembly.

5. Drilling apparatus, as claimed in claim 4, in which the angle throughwhich said drilling head'is tilted is less than the angle through whichsaid mast is tilted.

* I i l l l

1. Drilling apparatus comprising in combination, a base; rail meansmounted on said base to extend longitudinally in one general direction;a drilling machine assembly supported on said rail means for movementback and forth in said general direction; stop means limiting movementof said drilling machine assembly along said rail means between aforward drilling position and a retracted hoisting position; saiddrilling machine assembly including a drilling head to grip and rotatean upright drill rod when in the drilling position; power meansoperaable to move said drilling machine assembly between its drillingand hoisting positions; an upright mast having its lower end pivotallyconnected to said drilling machine assembly at a first pivot connection,to move back and forth with said drilling machine assembly; a rigid stayhaving one end pivotally connected, by a second pivot connection, to anupper part of said mast, and having its other end pivotally connected,by a third pivot connection, to an anchorage fixed relative to saidbase, whereby said mast is rotated about said second pivot connectionresponsive to movement of said drilling machine assembly between itsdrilling and hoisting positions; a hoist sheave support suspended fromthe upper part of said mast to be swingable about said second pivotconnection; and hoist sheave means mounted on said sheave support; saidrail means and said stop means defining the drilling and hoistingpositions of said drilling machine assembly in a manner such that, whensaid drilling machine assembly is in its drilling position, said firstpivot connection is in a first position and said second pivot connectionis in a second position and, when said drilling machine assembly is inits hoisting positio, said first pivot connection is in a third positionspaced from said second position by a distance equal to the spacingbetween said first and second positions, whereby said mast and said stayserve as a linkage assuring said second pivot connection remaining insaid second position so that the location of said sheave means isidentical in both the drilling and hoisting positions of said drillingmachine assembly.
 2. Drilling apparatus comprising, in combination, abase; rail means mounted on said base to extend longitudinally in onegeneral direction; a drilling machine assembly supported on said railmeans for movement back and forth in said general direction; stop meanslimiting movement of said drilling machine assembly along said railmeans between a forward drilling position and a retracted hoistingposition; said drilling machine assembly including a drilling head togrip and rotate an upright drill rod when in the drilling position;power means operable to move said drilling machine assembly between itsdrilling and hoisting positions; an upright mast having its lower endpivotally connected to said drilling machine assembly at a first pivotconnection, to move back and forth with said drilling machine assembly;a rigid stay having one end pivotally connected, by a second pivotconnection, to an upper part of said mast, and having its other endpivotally connected, by a third pivot connection, to an anchorage fixedrelative to said base, whereby said mast is rotated about said secondpivot connection responsive to movement of said drilling machineassembly between its drilling and hoisting positions; a hoist sheavesupport suspended from the upper part of said mast to be swingable aboutsaid second pivot connection; and hoist sheave means mounted on saidsheave support; said rail means and said stop means defining thedrilling and hoisting positions of said drilling machine assembly in amanner such that when said drilling machine assembly is in its drillingposition, said first pivot connection is spaced forwardly apredetermined distance from a vertical plane through said second pivotconnection and transverse to said predetermined distance and, when saiddrilling machine is in its hoisting position, said first pivotconnection is spaced through a distance equal to said predetermineddistance rearwardly from said vertical plane, said mast and said stayserving as a linkaage to assure said second pivot connection, andconsequently said sheave means, remaining in the same location in boththe drilling and hoisting positions of said drilling machine assembly.3. Drilling apparatus, as claimed in claim 2, in which said drillingmachine assembly includes a winch drum and said sheave means comprises apair of sheave wheels mounted for rotation on said sheave support; oneof said sheave wheels being located directly above said winch drum whensaid drilling machine assembly is in its hoisting position; the other ofsaid sheave wheels being located directly above the drill hole duringboth the drilling and hoisting operations.
 4. Drilling apparatus, asclaimed in claim 2, in which said drilling machine assembly in movingfrom the drilling position to the hoisting position rotates about ahorizontal transverse axis to tilt said drilling head in the samedirection as the direction of tilt of said mast away from its originalupright position resulting from said movement of said drilling machineassembly.
 5. Drilling apparatus, as claimed in claim 4, in which theangle through which said drilling head is tilted is less than the anglethrough which said mast is tilted.